Insecticide-treated textiles such as mosquito nets and clothing are commonly used as an intervention in the fight against vector-borne diseases such as malaria, encephalitis, filariasis, leishmaniasis, and West Nile virus. Insecticides frequently used for the treatment of textiles include the pyrethroid class of insecticides, such as permethrin.
Washing of the textiles along with normal wear, particularly in the case of clothing, depletes the insecticide on the material, thereby eventually rendering them ineffective against the insect vectors. Currently, assays for insecticides such as pyrethroids can be provided by complex analytical techniques such as gas chromatography and high performance liquid chromatography (HPLC). Such techniques are well suited for insecticide analysis in production facilities, to assure that desired levels of the insecticides are impregnated into the materials.
However, it would be desirable to quantitatively assay these materials in use in the field to assess the levels of insecticide, and thus effectiveness, so as to avoid the inadvertent exposure of personnel to insect vectors and thus vector-borne diseases. A suitable assay would have to be simple to use and inexpensive to produce. U.S. Patent Application Publication 2011/0033945 A1 discloses a colorimetric assay for the presence of type II pyrethroids, which are a class of pyrethroids containing an alpha cyano ester group obtained by esterification of a cyanohydrin. The assay comprises adding a base and then a mixture of a hydride donor and a hydride acceptor to a sample, and observing the sample for a color change. The assay is based on the detection of cyanide generated from the type II pyrethroid. However, permethrin, which does not contain an alpha cyano ester group, is not detectable in this assay.
In view of the foregoing, an unmet need exists for a simple and reliable quantitative assay of permethrin in textile materials.